“Hierarchical structure” is used herein in the ordinary sense of a “tree,” wherein there is only one route between any pair of nodes, and there is a notion of “toward top of the tree” (i.e. the root node, which is a node with no parent), and its opposite direction, toward a “leaf” or bottom node with no descendants, such that there are multiple levels of nodes, and no node can have more than one parent. Any node between the root node and a leaf node is referred to as an “intermediate node.” Any path within the structure starts at the root node and progresses down an intermediate node at each lower level until it terminates at a leaf node. A tree with n nodes has n−1 branches in the path between the root node and a leaf node.
Hierarchical structures such as file managers, taxonomies, and tables of contents, and particularly large or complex hierarchical file structures, contain multiple levels of nodes (folders and subfolders). Conventionally, an expand/collapse icon is displayed to the left of each node's name. This icon shows a “+” symbol if the node is collapsed (that is, if the descendant nodes (which may be document folders or files) in the levels under it are hidden). Clicking the icon while the “+” symbol is displayed causes the descendant nodes in the level directly under that node to display. The icon then displays a “−” symbol. In a similar fashion, clicking the icon while the “−” symbol is displayed causes the node to collapse—the icon then displays the “+” symbol again. All descendant nodes displayed under the original node are collapsed until the “+” symbol displayed next to them is clicked.
In current multilevel hierarchies, a branch of that structure can be collapsed and individual nodes in the hierarchy can only be expanded to the next display level with a single action. Expanding a branch to multiple display levels requires multiple actions and no indication of the number of nodes that will be exposed at a given display level is provided.
It is to the solution of these and other problems to which the present invention is directed.